When running Active Memory Sharing, the Collaborative Memory Manager (CMM)
may mark some pages as "loaned" with the hypervisor. Periodically, the
CMM will query the hypervisor for a loan request, which is a single signed
value. When kexec'ing into a kdump kernel, the CMM driver in the kdump
kernel is not aware of the pages the previous kernel had marked as "loaned",
so the hypervisor and the CMM driver are out of sync. Fix the CMM driver
to handle this scenario by ignoring requests to decrease the number of loaned
pages if we don't think we have any pages loaned. Pages that are marked as
"loaned" which are not in the balloon will automatically get switched to "active"
the next time we touch the page. This also fixes the case where totalram_pages
is smaller than min_mem_mb, which can occur during kdump.
Signed-off-by: NBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

When running Active Memory Sharing, pages can get marked as
"loaned" with the hypervisor by the CMM driver. This state gets
cleared by the system firmware when rebooting the partition.
When using kexec to boot a new kernel, this state never gets
cleared and the hypervisor and CMM driver can get out of sync
with respect to the number of pages currently marked "loaned".
Fix this by adding a reboot notifier to the CMM driver to deflate
the balloon and mark all pages as active.
Signed-off-by: NBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

__FUNCTION__ is gcc-specific, use __func__

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Noticed due to these wanings:

arch/powerpc/platforms/pseries/cmm.c:298: warning: initialization from incompatible pointer type
arch/powerpc/platforms/pseries/cmm.c:299: warning: initialization from incompatible pointer type
arch/powerpc/platforms/pseries/cmm.c:320: warning: initialization from incompatible pointer type
arch/powerpc/platforms/pseries/cmm.c:320: warning: initialization from incompatible pointer type
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Adds a collaborative memory manager, which acts as a simple balloon driver
for System p machines that support cooperative memory overcommitment
(CMO).

Adds a platform configuration option for CMO called PPC_SMLPAR.
Signed-off-by: NBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: NRobert Jennings <rcj@linux.vnet.ibm.com>
Acked-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>